We support online log resizing by replicating the current ib_logfile0
to a new file ib_logfile101, which will eventually replace the
ib_logfile0 on the first applicable log checkpoint.
Unless the log is located in a persistent memory file system (PMEM),
an attempt to SET GLOBAL innodb_log_file_size to less than
innodb_log_buffer_size will be refused. (With PMEM, a.k.a. mmap()
based log, that parameter has no meaning.)
Should the server be killed while the log was being resized,
both files ib_logfile0 and ib_logfile101 may exist on startup,
and since commit 3b06415cb8
the extra file ib_logfile101 will be removed.
We will initiate checkpoint flushing by invoking buf_flush_ahead(),
to let buf_flush_page_cleaner() write out pages until the
buf_flush_async_lsn target has been reached.
On a log checkpoint, if the new checkpoint LSN is not older than
log_sys.resize_lsn (the start LSN of the ib_logfile101),
we can switch files and complete the log resizing. Else, we will
attempt to switch files on the next checkpoint.
Log resizing can be aborted by killing the connection that is
executing the SET GLOBAL statement.
If the ib_logfile101 wraps around to the beginning, we must
advance the log_sys.resize_lsn. In the resized log file,
the sequence bit will always be written as 1 (no wrap-around).
The log will be duplicated in log_t::resize_write(), invoked by
mtr_t::finish_write().
When the log is being written via system calls (not PMEM), the initial
log_sys.resize_lsn is the current log_sys.first_lsn, plus an integer
multiple of log_sys.block_size, corresponding to the LSN at the start
of the block that was written by log_sys.write_lsn. The log_sys.resize_buf
will be of the same size as the log_sys.buf. During resizing, the
contents of log_sys.buf and log_sys.resize_buf will be identical,
except that the sequence bit of each mini-transaction will always be 1 in
log_sys.resize_buf. If resizing is in progress, log_t::write_buf()
will write log_sys.resize_buf to log_sys.resize_log (ib_logfile101).
If the file would wrap around, the buffer will be written to
log_sys.START_OFFSET and the log_sys.resize_lsn advanced accordingly.
When using mmap() on /dev/shm or a PMEM mount -o dax file system,
the initial log_sys.resize_lsn will be the log_sys.lsn at the time
the resizing is initiated. If the log file wraps around during resizing,
then the log_sys.resize_lsn will be advanced by
(log_sys.resize_target - log_sys.START_OFFSET).
log_t::resize_start(), log_t::resize_abort(), log_t::write_checkpoint():
Unless the log is mmap() based, acquire flush_lock and write_lock.
In any case, acquire exclusive log_sys.latch to prevent race conditions.
log_t::resize_rename(): Renamed from log_t::rename_resized(),
and moved some code to the previous sole caller srv_start().
Thanks to Vladislav Vaintroub for helpful review comments
and to Matthias Leich for testing this, in particular, testing
crash recovery, multiple concurrent SET GLOBAL innodb_log_file_size
and frequently killed connections.
- Make innodb_ft_cache_size & innodb_ft_total_cache_size are dynamic
variable and increase the maximum value of innodb_ft_cache_size to
512MB for 32-bit system and 1 TB for 64-bit system and set
innodb_ft_total_cache_size maximum value to 1 TB for 64-bit system.
- Print warning if the fts cache exceeds the innodb_ft_cache_size
and also unlock the cache if fts cache memory reduces less than
innodb_ft_cache_size.
As a follow-up to MDEV-27734 Set innodb_change_buffering=none by default
we mark the option innodb_change_buffering deprecated, to inform users
of its future removal.
A prominent bottleneck in mtr_t::commit() is log_sys.mutex between
log_sys.append_prepare() and log_close().
User-visible change: The minimum innodb_log_file_size will be
increased from 1MiB to 4MiB so that some conditions can be
trivially satisfied.
log_sys.latch (log_latch): Replaces log_sys.mutex and
log_sys.flush_order_mutex. Copying mtr_t::m_log to
log_sys.buf is protected by a shared log_sys.latch.
Writes from log_sys.buf to the file system will be protected
by an exclusive log_sys.latch.
log_sys.lsn_lock: Protects the allocation of log buffer
in log_sys.append_prepare().
sspin_lock: A simple spin lock, for log_sys.lsn_lock.
Thanks to Vladislav Vaintroub for suggesting this idea, and for
reviewing these changes.
mariadb-backup: Replace some use of log_sys.mutex with recv_sys.mutex.
buf_pool_t::insert_into_flush_list(): Implement sorting of flush_list
because ordering is otherwise no longer guaranteed. Ordering by LSN
is needed for the proper operation of redo log checkpoints.
log_sys.append_prepare(): Advance log_sys.lsn and log_sys.buf_free by
the length, and return the old values. Also increment write_to_buf,
which was previously done in log_close().
mtr_t::finish_write(): Obtain the buffer pointer from
log_sys.append_prepare().
log_sys.buf_free: Make the field Atomic_relaxed,
to simplify log_flush_margin(). Use only loads and stores
to avoid costly read-modify-write atomic operations.
buf_pool.flush_list_requests: Replaces
export_vars.innodb_buffer_pool_write_requests
and srv_stats.buf_pool_write_requests.
Protected by buf_pool.flush_list_mutex.
buf_pool_t::insert_into_flush_list(): Do not invoke page_cleaner_wakeup().
Let the caller do that after a batch of calls.
recv_recover_page(): Invoke a minimal part of
buf_pool.insert_into_flush_list().
ReleaseBlocks::modified: A number of pages added to buf_pool.flush_list.
ReleaseBlocks::operator(): Merge buf_flush_note_modification() here.
log_t::set_capacity(): Renamed from log_set_capacity().
The aim of the InnoDB change buffer is to avoid delays when a leaf page
of a secondary index is not present in the buffer pool, and a record needs
to be inserted, delete-marked, or purged. Instead of reading the page into
the buffer pool for making such a modification, we may insert a record to
the change buffer (a special index tree in the InnoDB system tablespace).
The buffered changes are guaranteed to be merged if the index page
actually needs to be read later.
The change buffer could be useful when the database is stored on a
rotational medium (hard disk) where random seeks are slower than
sequential reads or writes.
Obviously, the change buffer will cause write amplification, due to
potentially large amount of metadata that is being written to the
change buffer. We will have to write redo log records for modifying
the change buffer tree as well as the user tablespace. Furthermore,
in the user tablespace, we must maintain a change buffer bitmap page
that uses 2 bits for estimating the amount of free space in pages,
and 1 bit to specify whether buffered changes exist. This bitmap needs
to be updated on every operation, which could reduce performance.
Even if the change buffer were free of bugs such as MDEV-24449
(potentially causing the corruption of any page in the system tablespace)
or MDEV-26977 (corruption of secondary indexes due to a currently
unknown reason), it will make diagnosis of other data corruption harder.
Because of all this, it is best to disable the change buffer by default.
In commit 9bc874a594 (MDEV-23497)
the configuration option innodb_read_only_compressed was introduced
to giver users advance notice of a plan to remove ROW_FORMAT=COMPRESSED
support for InnoDB.
Based on user feedback, this plan has been scrapped.
Even though ROW_FORMAT=COMPRESSED is a dead end and causes some
overhead for InnoDB data structures, we can live with that.
Now that we know that some users really want to keep using
ROW_FORMAT=COMPRESSED, the previous default value of the parameter
innodb_read_only_compressed=ON should be changed to OFF, to allow
smooth upgrades to 10.6 and later versions, without requiring users
to update any configuration file.
- Revert wrongly record embedded result files. These were either
recorded with normal server (not embedded) or an embedded server
with not default compile option. This can be seen that the committed
result file had replication variables which should never happen.
- Reverted back change of include/is_embedded.inc. One cannot check for
$MYSQL_EMBEDDED as this only tells if there exists an embedded
server, not if the current server we are testing is the embedded
server. This could easily be verified by doing
'mtr sys_vars.sysvars_server_embedded'. This would fail with a wrong
result instead of being marked as skipped as --embedded was not
used.
This commit implements two phase binloggable ALTER.
When a new
@@session.binlog_alter_two_phase = YES
ALTER query gets logged in two parts, the START ALTER and the COMMIT
or ROLLBACK ALTER. START Alter is written in binlog as soon as
necessary locks have been acquired for the table. The timing is
such that any concurrent DML:s that update the same table are either
committed, thus logged into binary log having done work on the old
version of the table, or will be queued for execution on its new
version.
The "COMPLETE" COMMIT or ROLLBACK ALTER are written at the very point
of a normal "single-piece" ALTER that is after the most of
the query work is done. When its result is positive COMMIT ALTER is
written, otherwise ROLLBACK ALTER is written with specific error
happened after START ALTER phase.
Replication of two-phase binloggable ALTER is
cross-version safe. Specifically the OLD slave merely does not
recognized the start alter part, still being able to process and
memorize its gtid.
Two phase logged ALTER is read from binlog by mysqlbinlog to produce
BINLOG 'string', where 'string' contains base64 encoded
Query_log_event containing either the start part of ALTER, or a
completion part. The Query details can be displayed with `-v` flag,
similarly to ROW format events. Notice, mysqlbinlog output containing
parts of two-phase binloggable ALTER is processable correctly only by
binlog_alter_two_phase server.
@@log_warnings > 2 can reveal details of binlogging and slave side
processing of the ALTER parts.
The current commit also carries fixes to the following list of
reported bugs:
MDEV-27511, MDEV-27471, MDEV-27349, MDEV-27628, MDEV-27528.
Thanks to all people involved into early discussion of the feature
including Kristian Nielsen, those who helped to design, implement and
test: Sergei Golubchik, Andrei Elkin who took the burden of the
implemenation completion, Sujatha Sivakumar, Brandon
Nesterenko, Alice Sherepa, Ramesh Sivaraman, Jan Lindstrom.
mtr is checking the wrong path for the embedded executable
on out of tree builds.
The is_embedded.inc tests are also checking the version rather
than the MTR MYSQL_EMBEDDED environment variable.
As a result, a few tests are out of date in the result recordings.
The InnoDB redo log used to be formatted in blocks of 512 bytes.
The log blocks were encrypted and the checksum was calculated while
holding log_sys.mutex, creating a serious scalability bottleneck.
We remove the fixed-size redo log block structure altogether and
essentially turn every mini-transaction into a log block of its own.
This allows encryption and checksum calculations to be performed
on local mtr_t::m_log buffers, before acquiring log_sys.mutex.
The mutex only protects a memcpy() of the data to the shared
log_sys.buf, as well as the padding of the log, in case the
to-be-written part of the log would not end in a block boundary of
the underlying storage. For now, the "padding" consists of writing
a single NUL byte, to allow recovery and mariadb-backup to detect
the end of the circular log faster.
Like the previous implementation, we will overwrite the last log block
over and over again, until it has been completely filled. It would be
possible to write only up to the last completed block (if no more
recent write was requested), or to write dummy FILE_CHECKPOINT records
to fill the incomplete block, by invoking the currently disabled
function log_pad(). This would require adjustments to some logic around
log checkpoints, page flushing, and shutdown.
An upgrade after a crash of any previous version is not supported.
Logically empty log files from a previous version will be upgraded.
An attempt to start up InnoDB without a valid ib_logfile0 will be
refused. Previously, the redo log used to be created automatically
if it was missing. Only with with innodb_force_recovery=6, it is
possible to start InnoDB in read-only mode even if the log file
does not exist. This allows the contents of a possibly corrupted
database to be dumped.
Because a prepared backup from an earlier version of mariadb-backup
will create a 0-sized log file, we will allow an upgrade from such
log files, provided that the FIL_PAGE_FILE_FLUSH_LSN in the system
tablespace looks valid.
The 512-byte log checkpoint blocks at 0x200 and 0x600 will be replaced
with 64-byte log checkpoint blocks at 0x1000 and 0x2000.
The start of log records will move from 0x800 to 0x3000. This allows us
to use 4096-byte aligned blocks for all I/O in a future revision.
We extend the MDEV-12353 redo log record format as follows.
(1) Empty mini-transactions or extra NUL bytes will not be allowed.
(2) The end-of-minitransaction marker (a NUL byte) will be replaced
with a 1-bit sequence number, which will be toggled each time when the
circular log file wraps back to the beginning.
(3) After the sequence bit, a CRC-32C checksum of all data
(excluding the sequence bit) will written.
(4) If the log is encrypted, 8 bytes will be written before
the checksum and included in it. This is part of the
initialization vector (IV) of encrypted log data.
(5) File names, page numbers, and checkpoint information will not be
encrypted. Only the payload bytes of page-level log will be encrypted.
The tablespace ID and page number will form part of the IV.
(6) For padding, arbitrary-length FILE_CHECKPOINT records may be written,
with all-zero payload, and with the normal end marker and checksum.
The minimum size is 7 bytes, or 7+8 with innodb_encrypt_log=ON.
In mariadb-backup and in Galera snapshot transfer (SST) scripts, we will
no longer remove ib_logfile0 or create an empty ib_logfile0. Server startup
will require a valid log file. When resizing the log, we will create
a logically empty ib_logfile101 at the current LSN and use an atomic rename
to replace ib_logfile0 with it. See the test innodb.log_file_size.
Because there is no mandatory padding in the log file, we are able
to create a dummy log file as of an arbitrary log sequence number.
See the test mariabackup.huge_lsn.
The parameter innodb_log_write_ahead_size and the
INFORMATION_SCHEMA.INNODB_METRICS counter log_padded will be removed.
The minimum value of innodb_log_buffer_size will be increased to 2MiB
(because log_sys.buf will replace recv_sys.buf) and the increment
adjusted to 4096 bytes (the maximum log block size).
The following INFORMATION_SCHEMA.INNODB_METRICS counters will be removed:
os_log_fsyncs
os_log_pending_fsyncs
log_pending_log_flushes
log_pending_checkpoint_writes
The following status variables will be removed:
Innodb_os_log_fsyncs (this is included in Innodb_data_fsyncs)
Innodb_os_log_pending_fsyncs (this was limited to at most 1 by design)
log_sys.get_block_size(): Return the physical block size of the log file.
This is only implemented on Linux and Microsoft Windows for now, and for
the power-of-2 block sizes between 64 and 4096 bytes (the minimum and
maximum size of a checkpoint block). If the block size is anything else,
the traditional 512-byte size will be used via normal file system
buffering.
If the file system buffers can be bypassed, a message like the following
will be issued:
InnoDB: File system buffers for log disabled (block size=512 bytes)
InnoDB: File system buffers for log disabled (block size=4096 bytes)
This has been tested on Linux and Microsoft Windows with both sizes.
On Linux, only enable O_DIRECT on the log for innodb_flush_method=O_DSYNC.
Tests in 3 different environments where the log is stored in a device
with a physical block size of 512 bytes are yielding better throughput
without O_DIRECT. This could be due to the fact that in the event the
last log block is being overwritten (if multiple transactions would
become durable at the same time, and each of will write a small
number of bytes to the last log block), it should be faster to re-copy
data from log_sys.buf or log_sys.flush_buf to the kernel buffer,
to be finally written at fdatasync() time.
The parameter innodb_flush_method=O_DSYNC will imply O_DIRECT for
data files. This option will enable O_DIRECT on the log file on Linux.
It may be unsafe to use when the storage device does not support
FUA (Force Unit Access) mode.
When the server is compiled WITH_PMEM=ON, we will use memory-mapped
I/O for the log file if the log resides on a "mount -o dax" device.
We will identify PMEM in a start-up message:
InnoDB: log sequence number 0 (memory-mapped); transaction id 3
On Linux, we will also invoke mmap() on any ib_logfile0 that resides
in /dev/shm, effectively treating the log file as persistent memory.
This should speed up "./mtr --mem" and increase the test coverage of
PMEM on non-PMEM hardware. It also allows users to estimate how much
the performance would be improved by installing persistent memory.
On other tmpfs file systems such as /run, we will not use mmap().
mariadb-backup: Eliminated several variables. We will refer
directly to recv_sys and log_sys.
backup_wait_for_lsn(): Detect non-progress of
xtrabackup_copy_logfile(). In this new log format with
arbitrary-sized blocks, we can only detect log file overrun
indirectly, by observing that the scanned log sequence number
is not advancing.
xtrabackup_copy_logfile(): On PMEM, do not modify the sequence bit,
because we are not allowed to modify the server's log file, and our
memory mapping is read-only.
trx_flush_log_if_needed_low(): Do not use the callback on pmem.
Using neither flush_lock nor write_lock around PMEM writes seems
to yield the best performance. The pmem_persist() calls may
still be somewhat slower than the pwrite() and fdatasync() based
interface (PMEM mounted without -o dax).
recv_sys_t::buf: Remove. We will use log_sys.buf for parsing.
recv_sys_t::MTR_SIZE_MAX: Replaces RECV_SCAN_SIZE.
recv_sys_t::file_checkpoint: Renamed from mlog_checkpoint_lsn.
recv_sys_t, log_sys_t: Removed many data members.
recv_sys.lsn: Renamed from recv_sys.recovered_lsn.
recv_sys.offset: Renamed from recv_sys.recovered_offset.
log_sys.buf_size: Replaces srv_log_buffer_size.
recv_buf: A smart pointer that wraps log_sys.buf[recv_sys.offset]
when the buffer is being allocated from the memory heap.
recv_ring: A smart pointer that wraps a circular log_sys.buf[] that is
backed by ib_logfile0. The pointer will wrap from recv_sys.len
(log_sys.file_size) to log_sys.START_OFFSET. For the record that
wraps around, we may copy file name or record payload data to
the auxiliary buffer decrypt_buf in order to have a contiguous
block of memory. The maximum size of a record is less than
innodb_page_size bytes.
recv_sys_t::parse(): Take the smart pointer as a template parameter.
Do not temporarily add a trailing NUL byte to FILE_ records, because
we are not supposed to modify the memory-mapped log file. (It is
attached in read-write mode already during recovery.)
recv_sys_t::parse_mtr(): Wrapper for recv_sys_t::parse().
recv_sys_t::parse_pmem(): Like parse_mtr(), but if PREMATURE_EOF would be
returned on PMEM, use recv_ring to wrap around the buffer to the start.
mtr_t::finish_write(), log_close(): Do not enforce log_sys.max_buf_free
on PMEM, because it has no meaning on the mmap-based log.
log_sys.write_to_buf: Count writes to log_sys.buf. Replaces
srv_stats.log_write_requests and export_vars.innodb_log_write_requests.
Protected by log_sys.mutex. Updated consistently in log_close().
Previously, mtr_t::commit() conditionally updated the count,
which was inconsistent.
log_sys.write_to_log: Count swaps of log_sys.buf and log_sys.flush_buf,
for writing to log_sys.log (the ib_logfile0). Replaces
srv_stats.log_writes and export_vars.innodb_log_writes.
Protected by log_sys.mutex.
log_sys.waits: Count waits in append_prepare(). Replaces
srv_stats.log_waits and export_vars.innodb_log_waits.
recv_recover_page(): Do not unnecessarily acquire
log_sys.flush_order_mutex. We are inserting the blocks in arbitary
order anyway, to be adjusted in recv_sys.apply(true).
We will change the definition of flush_lock and write_lock to
avoid potential false sharing. Depending on sizeof(log_sys) and
CPU_LEVEL1_DCACHE_LINESIZE, the flush_lock and write_lock could
share a cache line with each other or with the last data members
of log_sys.
Thanks to Matthias Leich for providing https://rr-project.org traces
for various failures during the development, and to
Thirunarayanan Balathandayuthapani for his help in debugging
some of the recovery code. And thanks to the developers of the
rr debugger for a tool without which extensive changes to InnoDB
would be very challenging to get right.
Thanks to Vladislav Vaintroub for useful feedback and
to him, Axel Schwenke and Krunal Bauskar for testing the performance.
.. to be the same as startup.
In resolving MDEV-27461, BUF_LRU_MIN_LEN (256) is the minimum number of
pages for the innodb buffer pool size. Obviously we need more than just
flushing pages. Taking the 16k page size and its default minimum, an
extra 25% is needed on top of the flushing pages to make a workable buffer
pool.
The minimum innodb_buffer_pool_chunk_size (1M) restricts the minimum
otherwise we'd have a pool made up of different chunk sizes.
The resulting minimum innodb buffer pool sizes are:
Page Size, Previously minimum (startup), with change.
4k 5M 2M
8k 5M 3M
16k 5M 5M
32k 24M 10M
64k 24M 20M
With this patch, SET GLOBAL innodb_buffer_pool_size minimums are
enforced.
The evident minimum system variable size for innodb_buffer_pool_size
is 2M, however this is only setable if using 4k page size. As
the order of the page_size and buffer_pool_size aren't fixed, we can't
hide this change.
Subsequent changes:
* innodb_buffer_pool_resize_with_chunks.test - raised of pool resize due to new
minimums. Chunk size also needed increase as the test was for
pool_size < chunk_size to generate a warning.
* Removed srv_buf_pool_min_size and replaced use with MYSQL_SYSVAR_NAME(buffer_pool_size).min_val
* Removed srv_buf_pool_def_size and replaced constant defination in
MYSQL_SYSVAR_LONGLONG(buffer_pool_size)
* Reordered ha_innodb to allow for direct use of MYSQL_SYSVAR_NAME(buffer_pool_size).min_val
* Moved buf_pool_size_align into ha_innodb to access to MYSQL_SYSVAR_NAME(buffer_pool_size).min_val
* loose-innodb_disable_resize_buffer_pool_debug is needed in the
innodb.restart.opt test so that under debug mode, resizing of the
innodb buffer pool can occur.
The previous default innodb_buffer_pool_chunk_size of 128M
made sense when the innodb buffer pool size was a few GB.
When the pool size is 128GB this means the chunk size is 0.1%
of this. Fine tuning the buffer pool size on such a fine
increment doesn't make practical sense. Also on extremely
large buffer pool systems, initializing on the default 128M can
also take a considerable amount of time.
When large pages are enabled, the chunk size has to be a multiple
of an available large page size or memory allocation without
use can occur.
Previously the default 0 was documented as disabling resizing.
With srv_buf_pool_chunk_unit > 0 assertions in the code and the
minimium value set, I doubt this was ever the case.
As such the autosizing (based on default 0) takes place as follows:
* a 64th of the innodb_buffer_pool_size
* if large pages, this is rounded down the the nearest multiple
of the large page size.
* If less than 1MB, set to 1MB.
This does mean the new default innodb_buffer_pool_chunk size is
2MB, derived form the above formular with 128MB as the buffer pool
size.
The innodb_buffer_pool_chunk_size is changed to a size_t for
better compatiblity with the memory allocations which use size_t.
The previous upper limit is changed to the maxium of a size_t. The
maximium value used is the buffer pool size anyway.
Getting this default value of the chunk size to a more practical
size facilitates further development of more automated resizing
without significant overhead or memory fragmentation.
innodb_buffer_pool_resize test adjusted based on 1M default
chunk size thanks Wlad.
